<% if post.calculate_score.to_i < 0 %>
  <%= "<span class=\"red\">" %>
<% elsif post.calculate_score.to_i > 0 %>
  <%= "<span class=\"green\">" %>
<% else %>
  <%="<span>"%>
  <%end%>
  <%= "[ " + post.calculate_score.to_s + " ]" %>
<%="</span>"%>